/*! \page Vmc_methodDoc Variational Monte Carlo method

Keyword: VMC

\section description Description

Evaluates the expectation value \f$ <\Psi|H|\Psi>/<\Psi|\Psi> \f$
stochastically.


\section options Options

\subsection reqopt Required 

No options are required.

\subsection optopt Optional

<table>
<tr> <td> <b>Option</b> <td> <b>Type</b> <td> <b> Default </b> 
     <td> <b>Description</b>
<tr> <td> NCONFIG  <td> Integer <td> 1 <td> Number of sample points to use at one time per processor
<tr> <td> NSTEP <td> Integer <td> 100 <td>  Number of average points to take in a block.
<tr> <td> NBLOCK <td> Integer <td> 100 <td>   Number of blocks to take
<tr> <td> TIMESTEP <td> Float <td> 1.0 <td>  A measure of how large each Metropolis move
should be.  Adjust such that the acceptance ratio is somewhat greater than
0.5.  If this is not specified, then the timestep will automatically be adjusted.
<tr> <td> NDECORR   <td> Integer <td> 2 
     <td>  Number of Metropolis steps to take before evaluating the energy.
           Since VMC steps don't require an energy evaluation, this serves
           to decorrelate the averaging points before doing an expensive
           evaluation of the energy(mostly pseudopotentials).

<tr> <td> STORECONFIG <td> String <td> runid.config <td> Write the configurations to 
this file every block.  
<tr> <td> READCONFIG <td> String <td> runid.config <td> Read from a configuration file
previously written by STORECONFIG. If this file is absent, then new configurations will be generated.
<tr> <td> AVERAGE,<br>DENSITY,<br>NONLOCAL_DENSITY <td> Section <td> empty 
     <td> Sections for evaluation of \ref PropertiesDoc .
<tr> <td> LABEL <td> String <td> dmc <td> Label in the .log file.
</table>

\subsection optadvanced Advanced
<table>
<tr> <td> GUIDETYPE <td> String <td> SUMSQUARES 
     <td> Possible options: SUMSQUARES(\f$ \Psi_T^2 = \Psi_1^2+\Psi_2^2 \f$), 
      SUM(\f$ (\Psi_1 + \Psi_2)^2 \f$), FIRST(\f$ \Psi_T = \Psi_1 \f$). Specify
the importance-sampling function. This will importance-sample <b> only</b>
with respect to wave functions defined in the TRIALFUNC section.  Ones
defined in AUX_WF/AUX_SYS will not be used, since they are auxillary, not
guiding functions.
<tr> <td> DYNAMICS <td> Section <td> {&nbsp;SPLIT&nbsp;}
     <td> Choose a dynamics generator (i.e., a strategy of the stochastic
     sampling). Possible options are { SPLIT } and { UNR }. Use UNR
     when you don't have pseudopotentials. Further possibilities of
     fine tuning are described on the \ref DynamicsDoc page.

</table>


*/
